A semiconductor pressure sensor having a diaphragm formed by a semiconductor thin plate is fabricated in general. For example, Japanese Patent Laying-Open No. 04-009770 discloses a semiconductor pressure sensor constituted of three layers, i.e., a silicon thin plate, an insulating layer and a silicon support substrate. In this semiconductor pressure sensor, a through-hole is formed in the silicon support substrate, and another through-hole continuous with this through-hole is formed in the insulating layer. On the other hand, Japanese Patent Laying-Open No. 2002-350259 discloses a semiconductor pressure sensor having a silicon support substrate provided with a through hole and an insulating layer not provided with a through-hole but remaining in a state at the time of formation of an SOI (Silicon On Insulator) substrate.
In each of the aforementioned semiconductor pressure sensors, the silicon thin plate positioned on an extension of the through-hole provided in the silicon support substrate functions as a diaphragm deformed by a pressure.
Patent Document 1: Japanese Patent Laying-Open No. 04-009770
Patent Document 2: Japanese Patent Laying-Open No. 2002-350259